Electrocatalytic oxidation of d-glucose at nanoporous Au and Au-Ag alloy electrodes in alkaline aqueous solutions

Nanoporous Au-Ag alloys with different Ag content were prepared by selective dissolution of Ag from Au₄₂Ag₅₈ alloy samples in HNO₃ solutions. With gradual dissolution of Ag component, the corroded Au-Ag alloy samples display typical bicontinuous nanoporous structures after dealloying for more than 10 min. The as-prepared nanostructured Au-Ag alloys exhibit obviously enhanced catalytic activity towards the electrooxidation of d-glucose as compared with the uncorroded Au₄₂Ag₅₈ alloy. It is of interest that the existence of a tiny amount of silver in the corroded Au-Ag alloys is very advantageous to enhancing their catalytic activity for the electrooxidation of glucose. The new finding was confirmed by the significant enhancement of the catalytic activity of a nanoporous gold (NPG) electrode after modification with a monolayer of Ag atoms underpotentially deposited (UPD). The nanoporous Au-Ag alloys with appropriate amount of Ag and the NPGs modified with Ag UPD monolayers are thus expected to be promising electrocatalysts for the development of glucose sensors and glucose fuel cells.